<template>
    <div>
        <h2>当前求和为：{{sum}}</h2>
        <select v-model.number="n">
            <option value="1">1</option>
            <option value="2">2</option>
            <option value="3">3</option>
        </select>
        <button @click="increment">+</button>
        <button @click="decrement">-</button>
        <button @click="incrementOdd">当前和为奇数再加</button>
        <button @click="incrementWait">等一等再加</button>
    </div>
</template>

<script>
    export default{
        name: "Count",
        data(){
            return {
                n: 1,       // 用户选择的数字
                sum: 0,   // 当前的和
            }
        },
        methods:{
            increment(){
                this.sum += this.n
            },
            decrement(){
                if(this.sum <= 0){
                    alert('不能再减了')
                    return
                }
                this.sum -= this.n
            },
            incrementOdd(){
                if(this.sum % 2){
                    this.sum += this.n
                }
            },
            incrementWait(){
                setTimeout(()=>{
                    this.sum += this.n
                }, 1000)
            }
        }
    }
</script>

<style scoped>
    button{
        margin-left: 10px;
    }
</style>
